As is known in the art, asymmetries in a photovoltaic (PV) string caused by temperature variation, dirt, panel aging, panel orientation, and other factors can negatively impact tracking efficiency. To maximize energy extraction, distributed power conversion is employed to enable per-panel or sub-panel maximum-power-point tracking (MPPT). There are essentially three common architectures deployed in residential and commercial PV installations for delivering power to the grid: (1) string inverter, (2) micro-inverter, and (3) DC-DC series power supplies working in concert with a string inverter. Each of these architectures has limitations.
For example, the existing approaches are typically constructed with magnetic components, possibly purchased on a per-panel basis. Even at high switching frequencies where magnetic component size can be minimized or eliminated by using air core or parasitic wire inductance, these components constrain manufacturing cost. High frequency switching may also complicate electromagnetic interface created by the distributed converters, as the frequencies approach allocated FCC bands.